Case IH 3533 (DTC 9D6E) - ECU – Engine Control Module (ECM) or Aftertreatment Control Module (ACM): CAN timeout error from downstream NOx sensor

The control module has lost communication with the downstream Nitrogen Oxide (NOx) sensor over the Controller Area Network (CAN) data bus. When the module stops receiving data updates from this sensor within the expected timeframe, it triggers this timeout error.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Farmall series (110A, 120A, 130A, 140A)
• Magnum series (Magnum 180)

1. 1

   Inspect the wiring harness leading to the downstream NOx sensor (located directly after the SCR catalyst) for melting, chafing, or physical damage.

2. 2

   Disconnect the sensor and check the pins for corrosion, moisture, or pushed-out terminals.

3. 3

   Verify that the sensor is receiving proper operating voltage (typically 12V or 24V depending on the machine's system) and has a solid ground.

4. 4

   Measure the resistance across the CAN High and CAN Low pins at the sensor connector. Check for shorts to ground or shorts to power on the CAN lines.

5. 5

   Verify if other modules or sensors on the same CAN bus are communicating. If multiple devices are offline, the issue is likely a broken CAN wire or a failed terminating resistor rather than the NOx sensor itself.

1. 1

   Preparation

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical spikes. Allow the exhaust system to cool completely, as the SCR and tailpipe area will be extremely hot.

2. 2

   Locate the Sensor

   Locate the downstream NOx sensor, which is threaded into the exhaust pipe directly after the SCR catalyst.

3. 3

   Disconnect

   Unplug the electrical connector from the machine's wiring harness.

4. 4

   Removal

   Use a specialized NOx sensor socket or a wrench to carefully unthread the sensor from the exhaust pipe. (Penetrating oil may be required if the sensor is seized).

5. 5

   Installation

   Apply a small amount of anti-seize to the threads of the new sensor (if not pre-applied) being careful not to contaminate the sensor probe. Thread the new sensor into the exhaust and torque to OEM specifications.

6. 6

   Reconnect

   Route the wiring safely away from extreme heat sources and plug the connector back into the harness.

7. 7

   Clear Codes

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST) to the diagnostic port and clear the inactive fault codes.

8. 8

   Validation

   Start the engine and allow it to reach operating temperature. You may need to initiate a service regeneration via the EST to verify that the SCR system is functioning correctly and that the CAN timeout code does not return.